Unable to launch safari browser even in Simulator: error: Could not prepare mobile safari: Error: Couldn't find built in app in its home or temp dir!

Hmm, there’s a couple of things here possibly to try.
Forewarning: I have not run any Mobile Safari tests on the simulator. I have recently run them on an iphone without fail.

Things to note:

  1. When starting appium (node), I append the --safari flag.
  2. I noticed that you do not have an app parameter in your desired capabilities. I list app = "./apps/SafariLauncher.ipa" in there. This SafariLauncher.ipa was downloaded from github and provisioned with my company’s standard provisioning so it works on our devices.
  3. Make sure developer mode is turned on in your Safari preferences so that the remote debugger port is open.
  4. If you are using the simulator or a real device, you MUST run Safari before attempting to use Appium.

A couple of documentation references. You probably know this already, but just in case:

  1. http://appium.io/slate/en/master/?ruby#example > Automating mobile web apps
  2. Mobile Web automation on iOS real device – Safari
  3. https://github.com/appium/appium/blob/master/docs/en/writing-running-appium/mobile-web.md